DIRECTIONS FOR LABORATORY WORK 787 



(6) Sketch small area of myocardium from injected specimen of 

 cat's heart to show vascular supply (165). 



(7) Sketch from a demonstration slide (stained with methylene 

 blue) a small area of the myocardium, showing the manner of the nerve 

 supply (166). 



X. BLOOD 



(A) THE RED BLOOD CORPUSCLES (Erythroplastids, 'Erythro- 

 cytes). 



(1) Sterilize tip of finger or lobe of ear with an alcohol-ether solu- 

 tion, and allow to dry thoroughly. Sterilize a needle in the flame of a 

 Bunsen burner. Prick finger tip or lobe of ear, and mount a consider- 

 able drop of blood under a cover-glass. Examine quickly. Compare 

 color as viewed macroscopically and under the microscope. Note shape 

 and form of red corpuscles, as seen en face and in profile. Note the 

 formation of rouleaux. Sketch (167). After a time crenated corpuscles 

 appear near the edges due to evaporation of the blood plasma which in 

 consequence has become hypertonic. Sketch (168). Note also the white 

 glistening leucocytes, and the clumps of platelets. 



(2) Place on a slide a small drop of Ringer's solution (an isotonic 

 solution). Prick finger tip and touch a small drop of blood to the 

 Ringer's solution. Mount the mixture under a cover-glass supported 

 by a hair (or prepare the mixture on the cover-glass and mount as a 

 hanging 'drop over a hollow ground slide, sealing the cover-glass with 

 vaselin). Follow a red corpuscle as it floats and turns in a current, 

 noting carefully its form. What is the shape of the red blood corpuscle ? 

 Is it nucleated? Sketch (169). What is the significance of the cup- 

 shaped corpuscles? Sketch (170). Do rouleaux appear in the circu- 

 lating blood? Note also the white glistening round and irregular leu- 

 cocytes, and the granular masses of platelets. 



(3) Make successive mounts of blood in Ringer's solution and add 

 to (1) a drop of a one per cent solution of acetic acid; to (2) a drop 

 of a one per cent solution of tannic acid; to (3) a drop of a solution of 

 bile. Note the results and explain. How is the third result related to 

 the morbid condition known as jaundice or icterus? 



(4) Mount a drop of blood in distilled water (a hypotonic solution). 

 Follow the successive changes undergone by the red corpuscles. Sketch 

 (171). Explain. Recognize the final steps when blood shadows and 

 blood dust (hemokonia) appear. 



